diff --git a/src/main/java/dev/openfga/sdk/api/OpenFgaApi.java b/src/main/java/dev/openfga/sdk/api/OpenFgaApi.java
index 0ea565a2..f9b780c2 100644
--- a/src/main/java/dev/openfga/sdk/api/OpenFgaApi.java
+++ b/src/main/java/dev/openfga/sdk/api/OpenFgaApi.java
@@ -77,9 +77,17 @@ public OpenFgaApi(Configuration configuration) throws FgaInvalidParameterExcepti
     }
 
     public OpenFgaApi(Configuration configuration, ApiClient apiClient) throws FgaInvalidParameterException {
+        this(configuration, apiClient, new Telemetry(configuration));
+    }
+
+    public OpenFgaApi(Configuration configuration, ApiClient apiClient, Telemetry telemetry)
+            throws FgaInvalidParameterException {
+        if (telemetry == null) {
+            throw new IllegalArgumentException("Telemetry cannot be null");
+        }
         this.apiClient = apiClient;
         this.configuration = configuration;
-        this.telemetry = new Telemetry(this.configuration);
+        this.telemetry = telemetry;
 
         if (configuration.getCredentials().getCredentialsMethod() == CredentialsMethod.CLIENT_CREDENTIALS) {
             this.oAuth2Client = new OAuth2Client(configuration, apiClient);
@@ -146,7 +154,8 @@ private CompletableFuture<ApiResponse<BatchCheckResponse>> batchCheck(
 
         try {
             HttpRequest request = buildHttpRequest("POST", path, body, configuration);
-            return new HttpRequestAttempt<>(request, "batchCheck", BatchCheckResponse.class, apiClient, configuration)
+            return new HttpRequestAttempt<>(
+                            request, "batchCheck", BatchCheckResponse.class, apiClient, configuration, telemetry)
                     .addTelemetryAttributes(telemetryAttributes)
                     .attemptHttpRequest();
         } catch (ApiException e) {
@@ -202,7 +211,7 @@ private CompletableFuture<ApiResponse<CheckResponse>> check(
 
         try {
             HttpRequest request = buildHttpRequest("POST", path, body, configuration);
-            return new HttpRequestAttempt<>(request, "check", CheckResponse.class, apiClient, configuration)
+            return new HttpRequestAttempt<>(request, "check", CheckResponse.class, apiClient, configuration, telemetry)
                     .addTelemetryAttributes(telemetryAttributes)
                     .attemptHttpRequest();
         } catch (ApiException e) {
@@ -252,7 +261,8 @@ private CompletableFuture<ApiResponse<CreateStoreResponse>> createStore(
 
         try {
             HttpRequest request = buildHttpRequest("POST", path, body, configuration);
-            return new HttpRequestAttempt<>(request, "createStore", CreateStoreResponse.class, apiClient, configuration)
+            return new HttpRequestAttempt<>(
+                            request, "createStore", CreateStoreResponse.class, apiClient, configuration, telemetry)
                     .addTelemetryAttributes(telemetryAttributes)
                     .attemptHttpRequest();
         } catch (ApiException e) {
@@ -301,7 +311,7 @@ private CompletableFuture<ApiResponse<Void>> deleteStore(String storeId, Configu
 
         try {
             HttpRequest request = buildHttpRequest("DELETE", path, configuration);
-            return new HttpRequestAttempt<>(request, "deleteStore", Void.class, apiClient, configuration)
+            return new HttpRequestAttempt<>(request, "deleteStore", Void.class, apiClient, configuration, telemetry)
                     .addTelemetryAttributes(telemetryAttributes)
                     .attemptHttpRequest();
         } catch (ApiException e) {
@@ -357,7 +367,8 @@ private CompletableFuture<ApiResponse<ExpandResponse>> expand(
 
         try {
             HttpRequest request = buildHttpRequest("POST", path, body, configuration);
-            return new HttpRequestAttempt<>(request, "expand", ExpandResponse.class, apiClient, configuration)
+            return new HttpRequestAttempt<>(
+                            request, "expand", ExpandResponse.class, apiClient, configuration, telemetry)
                     .addTelemetryAttributes(telemetryAttributes)
                     .attemptHttpRequest();
         } catch (ApiException e) {
@@ -407,7 +418,8 @@ private CompletableFuture<ApiResponse<GetStoreResponse>> getStore(String storeId
 
         try {
             HttpRequest request = buildHttpRequest("GET", path, configuration);
-            return new HttpRequestAttempt<>(request, "getStore", GetStoreResponse.class, apiClient, configuration)
+            return new HttpRequestAttempt<>(
+                            request, "getStore", GetStoreResponse.class, apiClient, configuration, telemetry)
                     .addTelemetryAttributes(telemetryAttributes)
                     .attemptHttpRequest();
         } catch (ApiException e) {
@@ -463,7 +475,8 @@ private CompletableFuture<ApiResponse<ListObjectsResponse>> listObjects(
 
         try {
             HttpRequest request = buildHttpRequest("POST", path, body, configuration);
-            return new HttpRequestAttempt<>(request, "listObjects", ListObjectsResponse.class, apiClient, configuration)
+            return new HttpRequestAttempt<>(
+                            request, "listObjects", ListObjectsResponse.class, apiClient, configuration, telemetry)
                     .addTelemetryAttributes(telemetryAttributes)
                     .attemptHttpRequest();
         } catch (ApiException e) {
@@ -516,7 +529,8 @@ private CompletableFuture<ApiResponse<ListStoresResponse>> listStores(
 
         try {
             HttpRequest request = buildHttpRequest("GET", path, configuration);
-            return new HttpRequestAttempt<>(request, "listStores", ListStoresResponse.class, apiClient, configuration)
+            return new HttpRequestAttempt<>(
+                            request, "listStores", ListStoresResponse.class, apiClient, configuration, telemetry)
                     .addTelemetryAttributes(telemetryAttributes)
                     .attemptHttpRequest();
         } catch (ApiException e) {
@@ -572,7 +586,8 @@ private CompletableFuture<ApiResponse<ListUsersResponse>> listUsers(
 
         try {
             HttpRequest request = buildHttpRequest("POST", path, body, configuration);
-            return new HttpRequestAttempt<>(request, "listUsers", ListUsersResponse.class, apiClient, configuration)
+            return new HttpRequestAttempt<>(
+                            request, "listUsers", ListUsersResponse.class, apiClient, configuration, telemetry)
                     .addTelemetryAttributes(telemetryAttributes)
                     .attemptHttpRequest();
         } catch (ApiException e) {
@@ -628,7 +643,7 @@ private CompletableFuture<ApiResponse<ReadResponse>> read(
 
         try {
             HttpRequest request = buildHttpRequest("POST", path, body, configuration);
-            return new HttpRequestAttempt<>(request, "read", ReadResponse.class, apiClient, configuration)
+            return new HttpRequestAttempt<>(request, "read", ReadResponse.class, apiClient, configuration, telemetry)
                     .addTelemetryAttributes(telemetryAttributes)
                     .attemptHttpRequest();
         } catch (ApiException e) {
@@ -687,7 +702,12 @@ private CompletableFuture<ApiResponse<ReadAssertionsResponse>> readAssertions(
         try {
             HttpRequest request = buildHttpRequest("GET", path, configuration);
             return new HttpRequestAttempt<>(
-                            request, "readAssertions", ReadAssertionsResponse.class, apiClient, configuration)
+                            request,
+                            "readAssertions",
+                            ReadAssertionsResponse.class,
+                            apiClient,
+                            configuration,
+                            telemetry)
                     .addTelemetryAttributes(telemetryAttributes)
                     .attemptHttpRequest();
         } catch (ApiException e) {
@@ -749,7 +769,8 @@ private CompletableFuture<ApiResponse<ReadAuthorizationModelResponse>> readAutho
                             "readAuthorizationModel",
                             ReadAuthorizationModelResponse.class,
                             apiClient,
-                            configuration)
+                            configuration,
+                            telemetry)
                     .addTelemetryAttributes(telemetryAttributes)
                     .attemptHttpRequest();
         } catch (ApiException e) {
@@ -813,7 +834,8 @@ private CompletableFuture<ApiResponse<ReadAuthorizationModelsResponse>> readAuth
                             "readAuthorizationModels",
                             ReadAuthorizationModelsResponse.class,
                             apiClient,
-                            configuration)
+                            configuration,
+                            telemetry)
                     .addTelemetryAttributes(telemetryAttributes)
                     .attemptHttpRequest();
         } catch (ApiException e) {
@@ -899,7 +921,8 @@ private CompletableFuture<ApiResponse<ReadChangesResponse>> readChanges(
 
         try {
             HttpRequest request = buildHttpRequest("GET", path, configuration);
-            return new HttpRequestAttempt<>(request, "readChanges", ReadChangesResponse.class, apiClient, configuration)
+            return new HttpRequestAttempt<>(
+                            request, "readChanges", ReadChangesResponse.class, apiClient, configuration, telemetry)
                     .addTelemetryAttributes(telemetryAttributes)
                     .attemptHttpRequest();
         } catch (ApiException e) {
@@ -961,7 +984,8 @@ private CompletableFuture<ApiResponse<StreamResultOfStreamedListObjectsResponse>
                             "streamedListObjects",
                             StreamResultOfStreamedListObjectsResponse.class,
                             apiClient,
-                            configuration)
+                            configuration,
+                            telemetry)
                     .addTelemetryAttributes(telemetryAttributes)
                     .attemptHttpRequest();
         } catch (ApiException e) {
@@ -1016,7 +1040,7 @@ private CompletableFuture<ApiResponse<Object>> write(String storeId, WriteReques
 
         try {
             HttpRequest request = buildHttpRequest("POST", path, body, configuration);
-            return new HttpRequestAttempt<>(request, "write", Object.class, apiClient, configuration)
+            return new HttpRequestAttempt<>(request, "write", Object.class, apiClient, configuration, telemetry)
                     .addTelemetryAttributes(telemetryAttributes)
                     .attemptHttpRequest();
         } catch (ApiException e) {
@@ -1083,7 +1107,7 @@ private CompletableFuture<ApiResponse<Void>> writeAssertions(
 
         try {
             HttpRequest request = buildHttpRequest("PUT", path, body, configuration);
-            return new HttpRequestAttempt<>(request, "writeAssertions", Void.class, apiClient, configuration)
+            return new HttpRequestAttempt<>(request, "writeAssertions", Void.class, apiClient, configuration, telemetry)
                     .addTelemetryAttributes(telemetryAttributes)
                     .attemptHttpRequest();
         } catch (ApiException e) {
@@ -1145,7 +1169,8 @@ private CompletableFuture<ApiResponse<WriteAuthorizationModelResponse>> writeAut
                             "writeAuthorizationModel",
                             WriteAuthorizationModelResponse.class,
                             apiClient,
-                            configuration)
+                            configuration,
+                            telemetry)
                     .addTelemetryAttributes(telemetryAttributes)
                     .attemptHttpRequest();
         } catch (ApiException e) {
diff --git a/src/main/java/dev/openfga/sdk/api/auth/OAuth2Client.java b/src/main/java/dev/openfga/sdk/api/auth/OAuth2Client.java
index 73916e91..21f17c5a 100644
--- a/src/main/java/dev/openfga/sdk/api/auth/OAuth2Client.java
+++ b/src/main/java/dev/openfga/sdk/api/auth/OAuth2Client.java
@@ -78,7 +78,8 @@ private CompletableFuture<CredentialsFlowResponse> exchangeToken()
                 ApiClient.formRequestBuilder("POST", "", this.authRequest.buildFormRequestBody(), config);
         HttpRequest request = requestBuilder.build();
 
-        return new HttpRequestAttempt<>(request, "exchangeToken", CredentialsFlowResponse.class, apiClient, config)
+        return new HttpRequestAttempt<>(
+                        request, "exchangeToken", CredentialsFlowResponse.class, apiClient, config, telemetry)
                 .attemptHttpRequest()
                 .thenApply(ApiResponse::getData);
     }
diff --git a/src/main/java/dev/openfga/sdk/api/client/ApiExecutor.java b/src/main/java/dev/openfga/sdk/api/client/ApiExecutor.java
index a6271e34..3f6eac44 100644
--- a/src/main/java/dev/openfga/sdk/api/client/ApiExecutor.java
+++ b/src/main/java/dev/openfga/sdk/api/client/ApiExecutor.java
@@ -3,6 +3,7 @@
 import dev.openfga.sdk.api.configuration.Configuration;
 import dev.openfga.sdk.errors.ApiException;
 import dev.openfga.sdk.errors.FgaInvalidParameterException;
+import dev.openfga.sdk.telemetry.Telemetry;
 import java.io.IOException;
 import java.net.http.HttpRequest;
 import java.util.Map;
@@ -29,6 +30,7 @@
 public class ApiExecutor {
     private final ApiClient apiClient;
     private final Configuration configuration;
+    private final Telemetry telemetry;
 
     /**
      * Constructs an ApiExecutor instance. Typically called via {@link OpenFgaClient#apiExecutor()}.
@@ -37,14 +39,29 @@ public class ApiExecutor {
      * @param configuration Client configuration
      */
     public ApiExecutor(ApiClient apiClient, Configuration configuration) {
+        this(apiClient, configuration, new Telemetry(configuration));
+    }
+
+    /**
+     * Constructs an ApiExecutor instance. Typically called via {@link OpenFgaClient#apiExecutor()}.
+     *
+     * @param apiClient API client for HTTP operations
+     * @param configuration Client configuration
+     * @param telemetry Telemetry instance for collecting metrics
+     */
+    public ApiExecutor(ApiClient apiClient, Configuration configuration, Telemetry telemetry) {
         if (apiClient == null) {
             throw new IllegalArgumentException("ApiClient cannot be null");
         }
         if (configuration == null) {
             throw new IllegalArgumentException("Configuration cannot be null");
         }
+        if (telemetry == null) {
+            throw new IllegalArgumentException("Telemetry cannot be null");
+        }
         this.apiClient = apiClient;
         this.configuration = configuration;
+        this.telemetry = telemetry;
     }
 
     /**
@@ -87,7 +104,7 @@ public <T> CompletableFuture<ApiResponse<T>> send(ApiExecutorRequestBuilder requ
 
             String methodName = "apiExecutor:" + requestBuilder.getMethod() + ":" + requestBuilder.getPath();
 
-            return new HttpRequestAttempt<>(httpRequest, methodName, responseType, apiClient, configuration)
+            return new HttpRequestAttempt<>(httpRequest, methodName, responseType, apiClient, configuration, telemetry)
                     .attemptHttpRequest();
 
         } catch (IOException e) {
diff --git a/src/main/java/dev/openfga/sdk/api/client/HttpRequestAttempt.java b/src/main/java/dev/openfga/sdk/api/client/HttpRequestAttempt.java
index 1a2d657f..88f33f52 100644
--- a/src/main/java/dev/openfga/sdk/api/client/HttpRequestAttempt.java
+++ b/src/main/java/dev/openfga/sdk/api/client/HttpRequestAttempt.java
@@ -37,13 +37,27 @@ public class HttpRequestAttempt<T> {
     public HttpRequestAttempt(
             HttpRequest request, String name, Class<T> clazz, ApiClient apiClient, Configuration configuration)
             throws FgaInvalidParameterException {
+        this(request, name, clazz, apiClient, configuration, new Telemetry(configuration));
+    }
+
+    public HttpRequestAttempt(
+            HttpRequest request,
+            String name,
+            Class<T> clazz,
+            ApiClient apiClient,
+            Configuration configuration,
+            Telemetry telemetry)
+            throws FgaInvalidParameterException {
         assertParamExists(configuration.getMaxRetries(), "maxRetries", "Configuration");
+        if (telemetry == null) {
+            throw new IllegalArgumentException("Telemetry cannot be null");
+        }
         this.apiClient = apiClient;
         this.configuration = configuration;
         this.name = name;
         this.request = request;
         this.clazz = clazz;
-        this.telemetry = new Telemetry(configuration);
+        this.telemetry = telemetry;
         this.telemetryAttributes = new HashMap<>();
     }
 
diff --git a/src/main/java/dev/openfga/sdk/api/client/OpenFgaClient.java b/src/main/java/dev/openfga/sdk/api/client/OpenFgaClient.java
index 98a29ae1..1afd3fce 100644
--- a/src/main/java/dev/openfga/sdk/api/client/OpenFgaClient.java
+++ b/src/main/java/dev/openfga/sdk/api/client/OpenFgaClient.java
@@ -9,6 +9,7 @@
 import dev.openfga.sdk.api.model.*;
 import dev.openfga.sdk.constants.FgaConstants;
 import dev.openfga.sdk.errors.*;
+import dev.openfga.sdk.telemetry.Telemetry;
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
@@ -22,6 +23,7 @@
 
 public class OpenFgaClient {
     private final ApiClient apiClient;
+    private Telemetry telemetry;
     private ClientConfiguration configuration;
     private OpenFgaApi api;
 
@@ -32,7 +34,8 @@ public OpenFgaClient(ClientConfiguration configuration) throws FgaInvalidParamet
     public OpenFgaClient(ClientConfiguration configuration, ApiClient apiClient) throws FgaInvalidParameterException {
         this.apiClient = apiClient;
         this.configuration = configuration;
-        this.api = new OpenFgaApi(configuration, apiClient);
+        this.telemetry = new Telemetry(configuration);
+        this.api = new OpenFgaApi(configuration, apiClient, telemetry);
     }
 
     /* ***********
@@ -63,7 +66,7 @@ public OpenFgaApi getApi() {
      * @return ApiExecutor instance
      */
     public ApiExecutor apiExecutor() {
-        return new ApiExecutor(this.apiClient, this.configuration);
+        return new ApiExecutor(this.apiClient, this.configuration, this.telemetry);
     }
 
     public void setStoreId(String storeId) {
@@ -76,7 +79,8 @@ public void setAuthorizationModelId(String authorizationModelId) {
 
     public void setConfiguration(ClientConfiguration configuration) throws FgaInvalidParameterException {
         this.configuration = configuration;
-        this.api = new OpenFgaApi(configuration, apiClient);
+        this.telemetry = new Telemetry(configuration);
+        this.api = new OpenFgaApi(configuration, apiClient, telemetry);
     }
 
     /* ********
diff --git a/src/main/java/dev/openfga/sdk/telemetry/Metrics.java b/src/main/java/dev/openfga/sdk/telemetry/Metrics.java
index 41f4d9af..88483262 100644
--- a/src/main/java/dev/openfga/sdk/telemetry/Metrics.java
+++ b/src/main/java/dev/openfga/sdk/telemetry/Metrics.java
@@ -6,8 +6,8 @@
 import io.opentelemetry.api.metrics.DoubleHistogram;
 import io.opentelemetry.api.metrics.LongCounter;
 import io.opentelemetry.api.metrics.Meter;
-import java.util.HashMap;
 import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
 
 /**
  * The Metrics class provides methods for creating and publishing metrics using OpenTelemetry.
@@ -24,8 +24,8 @@ public Metrics() {
 
     public Metrics(Configuration configuration) {
         this.meter = GlobalOpenTelemetry.get().getMeterProvider().get("openfga-sdk");
-        this.counters = new HashMap<>();
-        this.histograms = new HashMap<>();
+        this.counters = new ConcurrentHashMap<>();
+        this.histograms = new ConcurrentHashMap<>();
         this.configuration = configuration;
         if (this.configuration.getTelemetryConfiguration() == null) {
             this.configuration.telemetryConfiguration(new TelemetryConfiguration());
@@ -55,15 +55,9 @@ public LongCounter getCounter(Counter counter, Long value, Map<Attribute, String
                 || !configuration.getTelemetryConfiguration().metrics().containsKey(counter)) {
             return null;
         }
-        if (!counters.containsKey(counter.getName())) {
-            counters.put(
-                    counter.getName(),
-                    meter.counterBuilder(counter.getName())
-                            .setDescription(counter.getDescription())
-                            .build());
-        }
-
-        LongCounter counterInstance = counters.get(counter.getName());
+        LongCounter counterInstance = counters.computeIfAbsent(counter.getName(), name -> meter.counterBuilder(name)
+                .setDescription(counter.getDescription())
+                .build());
 
         if (value != null) {
             counterInstance.add(value, Attributes.prepare(attributes, counter, configuration));
@@ -87,16 +81,11 @@ public DoubleHistogram getHistogram(Histogram histogram, Double value, Map<Attri
             return null;
         }
 
-        if (!histograms.containsKey(histogram.getName())) {
-            histograms.put(
-                    histogram.getName(),
-                    meter.histogramBuilder(histogram.getName())
-                            .setDescription(histogram.getDescription())
-                            .setUnit(histogram.getUnit())
-                            .build());
-        }
-
-        DoubleHistogram histogramInstance = histograms.get(histogram.getName());
+        DoubleHistogram histogramInstance =
+                histograms.computeIfAbsent(histogram.getName(), name -> meter.histogramBuilder(name)
+                        .setDescription(histogram.getDescription())
+                        .setUnit(histogram.getUnit())
+                        .build());
 
         if (value != null) {
             histogramInstance.record(value, Attributes.prepare(attributes, histogram, configuration));
diff --git a/src/main/java/dev/openfga/sdk/telemetry/Telemetry.java b/src/main/java/dev/openfga/sdk/telemetry/Telemetry.java
index 1fdf4a0b..aa2c9f3d 100644
--- a/src/main/java/dev/openfga/sdk/telemetry/Telemetry.java
+++ b/src/main/java/dev/openfga/sdk/telemetry/Telemetry.java
@@ -6,8 +6,8 @@
  * The Telemetry class provides access to telemetry-related functionality.
  */
 public class Telemetry {
-    private Configuration configuration = null;
-    private Metrics metrics = null;
+    private final Configuration configuration;
+    private volatile Metrics metrics;
 
     public Telemetry(Configuration configuration) {
         this.configuration = configuration;
@@ -16,12 +16,19 @@ public Telemetry(Configuration configuration) {
     /**
      * Returns a Metrics singleton for collecting telemetry data.
      * If the Metrics singleton has not previously been initialized, it will be created.
+     * This method is thread-safe via double-checked locking.
      */
     public Metrics metrics() {
-        if (metrics == null) {
-            metrics = new Metrics(configuration);
+        Metrics result = metrics;
+        if (result == null) {
+            synchronized (this) {
+                result = metrics;
+                if (result == null) {
+                    result = new Metrics(configuration);
+                    metrics = result;
+                }
+            }
         }
-
-        return metrics;
+        return result;
     }
 }
diff --git a/src/test/java/dev/openfga/sdk/api/OpenFgaApiTest.java b/src/test/java/dev/openfga/sdk/api/OpenFgaApiTest.java
index b222fca2..6e8a7f55 100644
--- a/src/test/java/dev/openfga/sdk/api/OpenFgaApiTest.java
+++ b/src/test/java/dev/openfga/sdk/api/OpenFgaApiTest.java
@@ -2138,4 +2138,11 @@ DEFAULT_STORE_ID, DEFAULT_AUTH_MODEL_ID, new WriteAssertionsRequest())
         assertEquals(
                 "{\"code\":\"internal_error\",\"message\":\"Internal Server Error\"}", exception.getResponseData());
     }
+
+    @Test
+    public void shouldRejectNullTelemetry() {
+        assertThrows(
+                IllegalArgumentException.class,
+                () -> new OpenFgaApi(new Configuration().apiUrl("https://localhost"), new ApiClient(), null));
+    }
 }
diff --git a/src/test/java/dev/openfga/sdk/api/client/ApiExecutorTest.java b/src/test/java/dev/openfga/sdk/api/client/ApiExecutorTest.java
index 6db3cf50..af64a9ed 100644
--- a/src/test/java/dev/openfga/sdk/api/client/ApiExecutorTest.java
+++ b/src/test/java/dev/openfga/sdk/api/client/ApiExecutorTest.java
@@ -381,4 +381,18 @@ public void rawApi_throwsExceptionForNullResponseType() throws Exception {
                 ApiExecutorRequestBuilder.builder(HttpMethod.GET, "/test").build();
         assertThrows(IllegalArgumentException.class, () -> client.apiExecutor().send(request, null));
     }
+
+    @Test
+    public void twoParamConstructor_shouldCreateWithOwnTelemetry() throws Exception {
+        // Verifies the backward-compatible 2-param constructor works
+        ClientConfiguration config = new ClientConfiguration().apiUrl(fgaApiUrl).storeId(DEFAULT_STORE_ID);
+        ApiExecutor executor = new ApiExecutor(new ApiClient(), config);
+        assertNotNull(executor);
+    }
+
+    @Test
+    public void threeParamConstructor_shouldRejectNullTelemetry() {
+        ClientConfiguration config = new ClientConfiguration().apiUrl(fgaApiUrl).storeId(DEFAULT_STORE_ID);
+        assertThrows(IllegalArgumentException.class, () -> new ApiExecutor(new ApiClient(), config, null));
+    }
 }
diff --git a/src/test/java/dev/openfga/sdk/api/client/HttpRequestAttemptRetryTest.java b/src/test/java/dev/openfga/sdk/api/client/HttpRequestAttemptRetryTest.java
index 33020bb0..5d05b915 100644
--- a/src/test/java/dev/openfga/sdk/api/client/HttpRequestAttemptRetryTest.java
+++ b/src/test/java/dev/openfga/sdk/api/client/HttpRequestAttemptRetryTest.java
@@ -13,6 +13,7 @@
 import dev.openfga.sdk.errors.ApiException;
 import dev.openfga.sdk.errors.FgaApiInternalError;
 import dev.openfga.sdk.errors.FgaError;
+import dev.openfga.sdk.telemetry.Telemetry;
 import java.net.http.HttpRequest;
 import java.time.Duration;
 import java.time.Instant;
@@ -26,6 +27,7 @@ class HttpRequestAttemptRetryTest {
     private WireMockServer wireMockServer;
     private ClientConfiguration configuration;
     private ApiClient apiClient;
+    private Telemetry telemetry;
 
     @BeforeEach
     void setUp() {
@@ -39,6 +41,7 @@ void setUp() {
                 .minimumRetryDelay(Duration.ofMillis(10)); // Short delay for testing
 
         apiClient = new ApiClient();
+        telemetry = new Telemetry(configuration);
     }
 
     @AfterEach
@@ -73,7 +76,7 @@ void shouldRetryWith429AndRetryAfterHeader() throws Exception {
                 .build();
 
         HttpRequestAttempt<Void> attempt =
-                new HttpRequestAttempt<>(request, "test", Void.class, apiClient, configuration);
+                new HttpRequestAttempt<>(request, "test", Void.class, apiClient, configuration, telemetry);
 
         // When
         ApiResponse<Void> response = attempt.attemptHttpRequest().get();
@@ -110,7 +113,7 @@ void shouldRetryWith500AndRetryAfterHeaderForGetRequest() throws Exception {
                 .build();
 
         HttpRequestAttempt<Void> attempt =
-                new HttpRequestAttempt<>(request, "test", Void.class, apiClient, configuration);
+                new HttpRequestAttempt<>(request, "test", Void.class, apiClient, configuration, telemetry);
 
         // When
         ApiResponse<Void> response = attempt.attemptHttpRequest().get();
@@ -134,7 +137,7 @@ void shouldRetryWith500WithoutRetryAfterHeaderForPostRequest() throws Exception
                 .build();
 
         HttpRequestAttempt<Void> attempt =
-                new HttpRequestAttempt<>(request, "test", Void.class, apiClient, configuration);
+                new HttpRequestAttempt<>(request, "test", Void.class, apiClient, configuration, telemetry);
 
         // When & Then
         ExecutionException exception = assertThrows(
@@ -174,7 +177,7 @@ void shouldRetryWith500WithRetryAfterHeaderForPostRequest() throws Exception {
                 .build();
 
         HttpRequestAttempt<Void> attempt =
-                new HttpRequestAttempt<>(request, "test", Void.class, apiClient, configuration);
+                new HttpRequestAttempt<>(request, "test", Void.class, apiClient, configuration, telemetry);
 
         // When
         ApiResponse<Void> response = attempt.attemptHttpRequest().get();
@@ -198,7 +201,7 @@ void shouldNotRetryWith501() throws Exception {
                 .build();
 
         HttpRequestAttempt<Void> attempt =
-                new HttpRequestAttempt<>(request, "test", Void.class, apiClient, configuration);
+                new HttpRequestAttempt<>(request, "test", Void.class, apiClient, configuration, telemetry);
 
         // When & Then
         ExecutionException exception = assertThrows(
@@ -224,7 +227,7 @@ void shouldRespectMaxRetries() throws Exception {
                 .build();
 
         HttpRequestAttempt<Void> attempt =
-                new HttpRequestAttempt<>(request, "test", Void.class, apiClient, configuration);
+                new HttpRequestAttempt<>(request, "test", Void.class, apiClient, configuration, telemetry);
 
         // When & Then
         ExecutionException exception = assertThrows(
@@ -260,7 +263,7 @@ void shouldUseExponentialBackoffWhenNoRetryAfterHeader() throws Exception {
                 .build();
 
         HttpRequestAttempt<Void> attempt =
-                new HttpRequestAttempt<>(request, "test", Void.class, apiClient, configuration);
+                new HttpRequestAttempt<>(request, "test", Void.class, apiClient, configuration, telemetry);
 
         // When
         ApiResponse<Void> response = attempt.attemptHttpRequest().get();
@@ -301,7 +304,7 @@ void shouldHandleInvalidRetryAfterHeader() throws Exception {
                 .build();
 
         HttpRequestAttempt<Void> attempt =
-                new HttpRequestAttempt<>(request, "test", Void.class, apiClient, configuration);
+                new HttpRequestAttempt<>(request, "test", Void.class, apiClient, configuration, telemetry);
 
         // When
         ApiResponse<Void> response = attempt.attemptHttpRequest().get();
@@ -331,8 +334,8 @@ void shouldRetryNetworkErrorsWithExponentialBackoff() throws Exception {
                 .timeout(Duration.ofMillis(50)) // Short timeout to force connection error
                 .build();
 
-        HttpRequestAttempt<Void> attempt =
-                new HttpRequestAttempt<>(request, "test", Void.class, apiClient, networkConfig);
+        HttpRequestAttempt<Void> attempt = new HttpRequestAttempt<>(
+                request, "test", Void.class, apiClient, networkConfig, new Telemetry(networkConfig));
 
         Instant startTime = Instant.now();
 
@@ -371,8 +374,8 @@ void shouldHonorNetworkErrorRetryDelayTiming() throws Exception {
                 .timeout(Duration.ofMillis(50)) // Short timeout to force connection error quickly
                 .build();
 
-        HttpRequestAttempt<Void> attempt =
-                new HttpRequestAttempt<>(request, "test", Void.class, apiClient, networkConfig);
+        HttpRequestAttempt<Void> attempt = new HttpRequestAttempt<>(
+                request, "test", Void.class, apiClient, networkConfig, new Telemetry(networkConfig));
 
         Instant startTime = Instant.now();
 
@@ -408,7 +411,8 @@ void shouldUseExponentialBackoffForNetworkErrorsWithPreciseTiming() throws Excep
                 .timeout(Duration.ofMillis(500)) // Reasonable timeout
                 .build();
 
-        HttpRequestAttempt<Void> attempt = new HttpRequestAttempt<>(request, "test", Void.class, apiClient, dnsConfig);
+        HttpRequestAttempt<Void> attempt =
+                new HttpRequestAttempt<>(request, "test", Void.class, apiClient, dnsConfig, new Telemetry(dnsConfig));
 
         Instant startTime = Instant.now();
 
@@ -446,7 +450,8 @@ void shouldRetryOnUnknownHost() throws Exception {
                 .timeout(Duration.ofMillis(1000))
                 .build();
 
-        HttpRequestAttempt<Void> attempt = new HttpRequestAttempt<>(request, "test", Void.class, apiClient, dnsConfig);
+        HttpRequestAttempt<Void> attempt =
+                new HttpRequestAttempt<>(request, "test", Void.class, apiClient, dnsConfig, new Telemetry(dnsConfig));
 
         // When & Then
         ExecutionException exception = assertThrows(
@@ -506,8 +511,8 @@ void shouldRespectGlobalMinimumRetryDelayWithExponentialBackoff() throws Excepti
                 .maxRetries(2)
                 .minimumRetryDelay(Duration.ofMillis(100)); // Should act as floor for exponential backoff
 
-        HttpRequestAttempt<Void> attempt =
-                new HttpRequestAttempt<>(request, "test", Void.class, apiClient, globalConfig);
+        HttpRequestAttempt<Void> attempt = new HttpRequestAttempt<>(
+                request, "test", Void.class, apiClient, globalConfig, new Telemetry(globalConfig));
 
         Instant startTime = Instant.now();
 
@@ -556,8 +561,8 @@ void shouldUseRetryAfterHeaderEvenWhenSmallerThanGlobalMinimumDelay() throws Exc
                 .maxRetries(2)
                 .minimumRetryDelay(Duration.ofMillis(150)); // Should NOT override Retry-After
 
-        HttpRequestAttempt<Void> attempt =
-                new HttpRequestAttempt<>(request, "test", Void.class, apiClient, globalConfig);
+        HttpRequestAttempt<Void> attempt = new HttpRequestAttempt<>(
+                request, "test", Void.class, apiClient, globalConfig, new Telemetry(globalConfig));
 
         Instant startTime = Instant.now();
 
@@ -604,8 +609,8 @@ void shouldUseRetryAfterWhenLargerThanGlobalMinimumDelay() throws Exception {
                 .maxRetries(2)
                 .minimumRetryDelay(Duration.ofMillis(50)); // Should NOT override Retry-After: 100ms
 
-        HttpRequestAttempt<Void> attempt =
-                new HttpRequestAttempt<>(request, "test", Void.class, apiClient, globalConfig);
+        HttpRequestAttempt<Void> attempt = new HttpRequestAttempt<>(
+                request, "test", Void.class, apiClient, globalConfig, new Telemetry(globalConfig));
 
         Instant startTime = Instant.now();
 
@@ -643,8 +648,8 @@ void shouldRespectPerRequestMinimumRetryDelayOverride() throws Exception {
                 configuration.override(new dev.openfga.sdk.api.configuration.ConfigurationOverride()
                         .minimumRetryDelay(Duration.ofMillis(100)));
 
-        HttpRequestAttempt<Void> attempt =
-                new HttpRequestAttempt<>(request, "test", Void.class, apiClient, overriddenConfig);
+        HttpRequestAttempt<Void> attempt = new HttpRequestAttempt<>(
+                request, "test", Void.class, apiClient, overriddenConfig, new Telemetry(overriddenConfig));
 
         Instant startTime = Instant.now();
 
@@ -687,8 +692,8 @@ void shouldRespectPerRequestMaxRetriesOverride() throws Exception {
                     .POST(HttpRequest.BodyPublishers.ofString("{}"))
                     .build();
 
-            HttpRequestAttempt<Void> attempt =
-                    new HttpRequestAttempt<>(request, "check", Void.class, apiClient, effectiveConfig);
+            HttpRequestAttempt<Void> attempt = new HttpRequestAttempt<>(
+                    request, "check", Void.class, apiClient, effectiveConfig, new Telemetry(effectiveConfig));
             attempt.attemptHttpRequest().get();
         });
 
@@ -726,8 +731,8 @@ void shouldUseRetryAfterHeaderEvenWhenSmallerThanMinimumDelay() throws Exception
                 configuration.override(new dev.openfga.sdk.api.configuration.ConfigurationOverride()
                         .minimumRetryDelay(Duration.ofMillis(150)));
 
-        HttpRequestAttempt<Void> attempt =
-                new HttpRequestAttempt<>(request, "test", Void.class, apiClient, overriddenConfig);
+        HttpRequestAttempt<Void> attempt = new HttpRequestAttempt<>(
+                request, "test", Void.class, apiClient, overriddenConfig, new Telemetry(overriddenConfig));
 
         Instant startTime = Instant.now();
 
@@ -776,8 +781,8 @@ void shouldNotOverrideRetryAfterWhenItIsLargerThanMinimumDelayPerRequest() throw
         // Verify the override took effect
         assertEquals(Duration.ofMillis(500), overriddenConfig.getMinimumRetryDelay());
 
-        HttpRequestAttempt<Void> attempt =
-                new HttpRequestAttempt<>(request, "test", Void.class, apiClient, overriddenConfig);
+        HttpRequestAttempt<Void> attempt = new HttpRequestAttempt<>(
+                request, "test", Void.class, apiClient, overriddenConfig, new Telemetry(overriddenConfig));
 
         Instant startTime = Instant.now();
 
@@ -796,4 +801,16 @@ void shouldNotOverrideRetryAfterWhenItIsLargerThanMinimumDelayPerRequest() throw
         // Verify initial request + 1 retry = 2 total requests
         wireMockServer.verify(2, getRequestedFor(urlEqualTo("/test")));
     }
+
+    @Test
+    void shouldRejectNullTelemetry() {
+        HttpRequest request = HttpRequest.newBuilder()
+                .uri(java.net.URI.create("http://localhost:" + wireMockServer.port() + "/test"))
+                .GET()
+                .build();
+
+        assertThrows(
+                IllegalArgumentException.class,
+                () -> new HttpRequestAttempt<>(request, "test", Void.class, apiClient, configuration, null));
+    }
 }
diff --git a/src/test/java/dev/openfga/sdk/telemetry/TelemetryTest.java b/src/test/java/dev/openfga/sdk/telemetry/TelemetryTest.java
index e42efe64..7a2119f7 100644
--- a/src/test/java/dev/openfga/sdk/telemetry/TelemetryTest.java
+++ b/src/test/java/dev/openfga/sdk/telemetry/TelemetryTest.java
@@ -3,6 +3,11 @@
 import static org.assertj.core.api.Assertions.assertThat;
 
 import dev.openfga.sdk.api.configuration.Configuration;
+import java.util.List;
+import java.util.concurrent.CopyOnWriteArrayList;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
 import org.junit.jupiter.api.Test;
 
 class TelemetryTest {
@@ -18,4 +23,41 @@ void shouldBeASingletonMetricsInitialization() {
         // then
         assertThat(firstCall).isNotNull().isSameAs(secondCall);
     }
+
+    @Test
+    void shouldReturnSameMetricsInstanceUnderConcurrentAccess() throws InterruptedException {
+        // given
+        Telemetry telemetry = new Telemetry(new Configuration());
+        int threadCount = 10;
+        ExecutorService executor = Executors.newFixedThreadPool(threadCount);
+        CountDownLatch startLatch = new CountDownLatch(1);
+        List<Metrics> results = new CopyOnWriteArrayList<>();
+
+        try {
+            // when
+            for (int i = 0; i < threadCount; i++) {
+                executor.submit(() -> {
+                    try {
+                        startLatch.await();
+                        results.add(telemetry.metrics());
+                    } catch (InterruptedException e) {
+                        Thread.currentThread().interrupt();
+                    }
+                });
+            }
+            startLatch.countDown();
+            executor.shutdown();
+            boolean terminated = executor.awaitTermination(5, java.util.concurrent.TimeUnit.SECONDS);
+            assertThat(terminated).isTrue();
+
+            // then
+            assertThat(results).hasSize(threadCount);
+            Metrics expected = results.get(0);
+            assertThat(results).allSatisfy(m -> assertThat(m).isSameAs(expected));
+        } finally {
+            if (!executor.isTerminated()) {
+                executor.shutdownNow();
+            }
+        }
+    }
 }